当用户可以输入int和double时添加两个数字

Question

I need the program to run when a user enter for example 4 and 6.5 or vice versa. i have the if else running only when its either or and when it tries to run it for both at the same time i get a error code like this :

Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Unknown Source)
    at java.util.Scanner.next(Unknown Source)
    at java.util.Scanner.nextInt(Unknown Source)
    at java.util.Scanner.nextInt(Unknown Source)
    at class2.AddTwoNumbers.main(AddTwoNumbers.java:28)

Any assistance would be greatly appreciated

    public class AddTwoNumbers {

        public static void main(String[] args) {
    Scanner inputSource = new Scanner(System.in);
    Scanner runAgain = new Scanner(System.in);
    int input1, input2, result;
    double input3, input4, result2;

    String answer = null;

    do {

         System.out.println("Please enter two numbers: ");
    if(inputSource.hasNextInt()) {

      input1 = inputSource.nextInt();
      input2 = inputSource.nextInt();


      result = input1 + input2;
      System.out.println("The sum of " + input1 + " and " + input2 + " is " + result);

       } else if (!inputSource.hasNextInt()){

              input3 = inputSource.nextDouble();
              input4 = inputSource.nextDouble();

              result2 = input3 + input4;
              System.out.println("The sum of " + input3 + " and " + input4 + " is " + result2);

              } else if (inputSource.hasNextInt() ||   inputSource.hasNextDouble()){
                  input1 = inputSource.nextInt();
                  input3 = inputSource.nextDouble();

                  result2 = input1 + input3;
                  System.out.println("The sum of " + input1 + " and " + input3 + " is " + result2);
    }           
    System.out.println("Do you want to run this again? Enter Y for Yes or N for No: ");
             answer = runAgain.next();


           } while (answer != "N");

           inputSource.close();     
     }

}

Answer 1

In such case, it's makes more sense to read the inputs with double number = Double.parseDouble(inputSource.nextLine()); . This would work for both int and double inputs.

Your code becomes as simple as :

double input1 = Double.parseDouble(inputSource.nextLine());
double input2 = Double.parseDouble(inputSource.nextLine());
double result = input1 + input2;

Beside that, change while (answer != "N"); to while (!answer.equals("N")); .

Answer 2

use nextLine() method instead of nextInt() and parse it into double which will work for both int and double type

double result;
double input1=Double.parseDouble(inputSource.nextLine());
double input2=Double.parseDouble(inputSource.nextLine());
result=input1+input2;

and also change while (answer != "N"); with while (!answer.equals("N"));// since your are comparing string not character